Real-time coronary artery stenosis detection based on modern neural networks

Invasive coronary angiography remains the gold standard for diagnosing coronary artery disease, which may be complicated by both, patient-specific anatomy and image quality. Deep learning techniques aimed at detecting coronary artery stenoses may facilitate the diagnosis. However, previous studies have failed to achieve superior accuracy and performance for real-time labeling. Our study is aimed at confirming the feasibility of real-time coronary artery stenosis detection using deep learning methods. To reach this goal we trained and tested eight promising detectors based on different neural network architectures (MobileNet, ResNet-50, ResNet-101, Inception ResNet, NASNet) using clinical angiography data of 100 patients. Three neural networks have demonstrated superior results. The network based on Faster-RCNN Inception ResNet V2 is the most accurate and it achieved the mean Average Precision of 0.95, F1-score 0.96 and the slowest prediction rate of 3 fps on the validation subset. The relatively lightweight SSD MobileNet V2 network proved itself as the fastest one with a low mAP of 0.83, F1-score of 0.80 and a mean prediction rate of 38 fps. The model based on RFCN ResNet-101 V2 has demonstrated an optimal accuracy-to-speed ratio. Its mAP makes up 0.94, F1-score 0.96 while the prediction speed is 10 fps. The resultant performance-accuracy balance of the modern neural networks has confirmed the feasibility of real-time coronary artery stenosis detection supporting the decision-making process of the Heart Team interpreting coronary angiography findings

Modulating the Magnetic Properties of Copper(II)/Nitroxyl Heterospin Complexes by Suppression of the Jahn–Teller Distortion

A series of six-coordinate [Cu(L)L1][BF4]2 (L1 = 2,6-bis{1-oxyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-2-yl}pyridine) complexes are reported. Ferromagnetic coupling between the Cu and L1 ligand spins is enhanced by an L coligand with distal methyl substituents, which is attributed to a sterically induced suppression of its Jahn–Teller distortion

Synthesis and study of CuII complex with nitroxide, a jumping crystal analogue

We synthesized 1-ethylimidazolyl-substituted nitronyl nitroxides, i.e., 2-(1-ethylimidazol-4-yl)- (L4Et) and 2-(1-ethylimidazol-5-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide-1-oxyl (L5Et). The stable radical L5Et is an ethyl analog of 2-(1-methylimidazol-5-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide-1-oxyl (L5Me) described earlier, the reaction of which with Cu(hfac)2 (hfac is 1,1,1,5,5,5-hexafluoropentane-2,4-dionate) leads to the formation of the [Cu(hfac)2(L5Me)2] jumping crystals. The reaction of Cu(hfac)2 with L5Et with reagent ratios 1: 2 and 1: 1 yields heterospin complexes [Cu(hfac)2(L5Et)2] and [Cu(hfac)2L5Et]2, respectively. X-ray diffraction study of the mononuclear complex [Cu(hfac)2(L5Et)2] determined that the compound has a packing similar to that of jumping crystals studied earlier, with the only difference being that the O...O contacts between neigh- boring nitroxide groups were found to be 0.3—0.5 Å longer than in [Cu(hfac)2(L5Me)2]. As a result of the lengthening of these contacts, [Cu(hfac)2(L5Et)2] crystals lack chemomechanical activi- ty. We found that when cooling crystals of binuclear complex [Cu(hfac)2L5Et]2 below 50 K, the antiferromagnetic exchange between unpaired electrons of the >N—•O groups of neighboring molecules leads to the full spin-pairing of the nitroxides, with only the Cu2+ ions contributing to the residual paramagnetism of the compound